This manual was last updated June 16, 2007 for version 1.4.12 of msmtp.
Copyright (C) 2005, 2006, 2007 Martin Lambers
This program, including this manual, is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.This program, including this manual, is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
msmtp is an SMTP client.
In its default mode of operation, it reads a mail from standard input and sends it to a predefined SMTP server that takes care of proper delivery. Command line options and exit codes are compatible to sendmail.
Supported SMTP features include:
The best way to start is probably to have a look at the Examples section. See Examples.
In addition to sendmail mode, there are two other modes of operation:
Normally, a system wide configuration file and/or a user configuration file contain information about which SMTP server to use and how to use it, but almost all settings can also be configured on the command line.
The information about SMTP servers is organized in accounts. Each account describes one SMTP server: host name, authentication settings, TLS settings, and so on. Each configuration file can define multiple accounts.
msmtp supports a system wide configuration file and a user configuration file. Both are optional and need not exist.
If it exists and is readable, a system wide configuration file
SYSCONFDIR/msmtprc will be loaded, where SYSCONFDIR depends on
your platform. The default is /usr/local/etc.
Use --version to find out which directory your version uses.
If it exists and is readable, a user configuration file will be loaded
(~/.msmtprc by default). Accounts defined in the user configuration
file override accounts from the system configuration file. The user
configuration file must have no more permissions than user read/write.
Configuration data from either file can be changed by command line options.
A configuration file is a simple text file. Empty lines and comment lines (whose first non-blank character is '#') are ignored. Every other line must contain a command and may contain an argument to that command. The argument may be enclosed in double quotes (").
If the first character of a filename is the tilde (~), this tilde will be
replaced by $HOME. If a command accepts the argument `on', it also
accepts an empty argument and treats that as if it was `on'.
Commands form groups. Each group starts with the `account' command and defines the settings for one SMTP server.
See Examples.
provider.example for
joe@provider.example) or the fully qualified domain name of your host
(if available).
See Authentication.
~/.netrc, and if that fails, will prompt you for it.
See Authentication.
See Sendmail mode.
$USER or, if that fails, to
$LOGNAME or, if that fails, to the login name of the current user. The
domain part can be set with the `maildomain' command (see
maildomain). If the maildomain is empty, the envelope-from address will
only consist of the user name and not have a domain part.msmtp [option...] [--] recipient...msmtp [option...] -t [--] [recipient...]
msmtp [option...] --serverinfo
msmtp [option...]
--rmqs=(host|@domain|#queue)
Options override configuration file settings. They are compatible with sendmail where appropriate.
Most options in this category correspond to a configuration file command. Please refer to Configuration files for detailed information.
~/.msmtprc as the user configuration
file.
The following options are accepted but ignored for sendmail compatibility: `-Btype', `-bm', `-Fname', `-G', `-hN', `-i', `-L tag', `-m', `-n', `-O option=value', `-ox value', `-v'
There are three ways to choose the account to use. It depends on the circumstances which method is the best.
The standard exit codes from sysexits.h are used.
SYSCONFDIR/msmtprc'SYSCONFDIR is on your platform.
~/.msmtprc'~/.netrc'.netrc file contains login information. If a password is not found
in the configuration file, msmtp will search it in .netrc before
prompting the user for it. The syntax of .netrc is described in the
netrc(5) or ftp(1) manual page.
$USER, $LOGNAME'LOGNAME is only used if USER is unset.
$TMPDIR'Transport Layer Security (TLS) is a new name for Secure Socket Layer (SSL). The TLS 1.0 protocol is an updated version of the SSL 3.0 protocol. TLS and SSL mean the same thing.
Quoting from RFC2246, the TLS 1.0 protocol specification:
"The TLS protocol provides communications privacy over the Internet.
The protocol allows client/server applications to communicate in a way that
is designed to prevent eavesdropping, tampering, or message forgery."
SMTP servers can use TLS in one of two modes:
When TLS is started, the server sends a certificate to identify itself. This certificate contains information about the certificate owner, the certificate issuer, and the activation and expiration times of the certificate. This information can be displayed in server information mode. See Server information mode.
To use TLS, it is required to either enable full server certificate verification using the `tls_trust_file' command or `--tls-trust-file' option, or to disable all certificate checks using `tls_certcheck off' or `--tls-certcheck=off'. WARNING: When certificate checks are disabled, TLS/SSL sessions are vulnerable to man-in-the-middle attacks! See tls_trust_file, –tls-trust-file, tls_certcheck, –tls-certcheck.
If your system has a file that collects all system-wide trusted CA certificates, it is easiest to just use this in the `defaults' section of your configuration file. On Debian-based systems, for example, the adequate command would be `tls_trust_file /etc/ssl/certs/ca-certificates.crt'.
But you can also find out manually which CA certificate you need to trust. The following example works as of 2007-04-18.
For the Gmail SMTP server, you first issue the following command:
$ msmtp --serverinfo --host=smtp.gmail.com --tls=on --port=587 \
--tls-certcheck=off
The option `--port=587' is specific to Gmail and should not be used with other servers. The option `--tls-certcheck=off' allows msmtp to accept any certificate, so that it can print some information about it.
According to the output of this command, the common name of the server certificate issuer is "Thawte Premium Server CA". This means that you have to trust the Thawte CA to use full TLS security. You can download the Thawte CA certificate bundle from http://thawte.com/roots. You get a ZIP file with different certificates. The one you need for the `tls_trust_file' command is Thawte Server Roots/ThawtePremiumServerCA_b64.txt.
The following command should now succeed:
$ msmtp --serverinfo --host=smtp.gmail.com --tls=on --port=587 \
--tls-trust-file="Thawte Server Roots/ThawtePremiumServerCA_b64.txt"
If the server requests it, the client can send a certificate, too. This allows the server to verify the identity of the client. See the EXTERNAL mechanism in Authentication. The `tls_key_file'/`tls_cert_file' commands or the `--tls-key-file'/`--tls-cert-file' options can be used to set a client certificate. See tls_key_file/–tls-key-file, tls_cert_file/–tls-cert-file. Note that GnuTLS will only send a client certificate if it matches one of the CAs advertised by the server. If you set a client certificate but it is not send to the server, it probably was not issued by any CA that the server trusts.
Many SMTP servers require a client to authenticate itself before it is allowed to send mail.
Multiple authentication methods exist. Most SMTP servers support only some of them. Some methods send authentication data in plain text (or nearly plain text) to the server. These methods should only be used when TLS is active to prevent others from stealing the password. See Transport Layer Security.
By default, msmtp chooses a method automatically, and it will never choose one that puts the authentication data at risk. See below for details.
msmtp supports the following authentication methods:
It depends on the underlying authentication library and its version whether a particular method is supported or not. Use the --version to find out which methods are supported by your version of msmtp.
Authentication data can be set with the `user' and `password' commands
or with the `--user' option. See user, password, –user.
If no password is set but one is needed during authentication, msmtp will try to
find it in ~/.netrc, and if that fails, msmtp will prompt you for it.
The authentication method can be chosen with the `auth' command or `--auth' option, but it is usually sufficient to just use the `on' argument to let msmtp choose the method itself. See auth, –auth.
If msmtp chooses the method itself, it will never choose an insecure method. If TLS is active, all methods are considered secure in this context, because the connection to the server is protected by TLS. If TLS is not active, only the CRAM-MD5, DIGEST-MD5, and GSSAPI methods are considered secure in this context, because all the others methods put the authentication data at risk.
If you really want to risk your authentication data, you have to force msmtp to do that by manually setting the authentication method while TLS is off.
In situations such as delivery failure or very long delivery delay, the mail system often generates a message for the sender of the mail in question, informing him about the difficulties.
Delivery Status Notification (DSN) requests, defined in RFC 3461, try to give the sender of the mail control about how and when these DSN messages are sent. The SMTP server must support the DSN extension. See Server information mode.
A first parameter controls when such messages should be generated: never, on delivery failure, on delivery delay, and/or on success. This can be set with `dsn_notify'/`--dsn-notify', see dsn_notify/–dsn-notify.
A second parameter controls how much of the original mail should be contained in a DSN message: only the headers, or the full mail. This can be set with `dsn_return'/`--dsn-return', see dsn_return/–dsn-return. Note that this parameter only applies to DSNs that indicate delivery failure for at least one recipient. If a DSN contains no indications of delivery failure, only the headers of the message are returned.
The SMTP server expects a sender mail address for each mail. This is the envelope-from address. It is independent of the From header (because it is part of the mail envelope, not of the mail itself), but in most cases both addresses are the same.
Envelope-from addresses can be generated automatically (when `auto_from' is enabled with the `auto_from' command or `--auto-from' option) or set explicitly with the `from' command and `--from' option. See auto_from, from.
When `auto_from' is enabled, an envelope-from address of the form
user@domain will be generated. The local part will be set to $USER or,
if that fails, to $LOGNAME or, if that fails, to the login name of the
current user. The domain part can be set with the `maildomain' command
and `--maildomain' option (see maildomain). If the maildomain is
empty, the envelope-from address will only consist of the user name and not
have a domain part.
Logging is enabled on a per account basis. If it is enabled, msmtp will generate one log line for each mail it tries to send via the account in question.
The line will include the following information:
host=hostname
tls=(on|off)
auth=(on|off)
user=name
from=address
recipients=addr1,addr2,...
mailsize=number
smtpstatus=number,
smtpmsg='message'. Multiline SMTP messages will be concatenated into one
line.
errormsg='message'
sysexits.h; `EX_OK' indicates
success): exitcode=EX_...
If a logfile is given with the `logfile' command or `--logfile' option, this log line will be prepended with the current date and time and appended to the specified file. See logfile, –logfile.
If syslog logging is enabled with the `syslog' command or `--syslog' option, the log line is passed to the syslog service with the specified facility. See syslog, –syslog.
msmtp transmits mails unaltered to the SMTP server, with one exception: the Bcc header(s) will be removed before the transmission. This behavior can be changed with the `keepbcc' command and `--keepbcc' option, see keepbcc/–keepbcc.
In server information mode, msmtp prints as much information about the SMTP server as it can get and then exits.
The SMTP features that can be detected are:
If TLS is activated for server information mode, the following information will be printed about the SMTP server's TLS certificate (if available):
Remote Message Queue Starting (RMQS) is defined in RFC 1985. It is a way for a client to request that a server start the processing of its mail queues for messages that are waiting at the server for the client machine. If any messages are at the server for the client, then the server creates a new SMTP session and sends the messages at that time.
msmtp can only send the request (using the ETRN SMTP command); a mail server on the client side should then accept the connection of the remote SMTP server to receive the mail.
RMQS requests can be sent with the `--rmqs' option (see –rmqs). Destinations defined in RFC 1985 are:
# A system wide configuration is optional.
# If it exists, it usually defines a default account.
# This allows msmtp to be used like /usr/sbin/sendmail.
account default
# The SMTP smarthost.
host mailhub.oursite.example
# Construct envelope-from addresses of the form "user@oursite.example".
#auto_from on
#maildomain oursite.example
# Use TLS.
#tls on
#tls_trust_file /etc/ssl/certs/ca-certificates.crt
# Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
syslog LOG_MAIL
# Set default values for all following accounts.
defaults
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile ~/.msmtp.log
# A freemail service
account freemail
host smtp.freemail.example
from joe_smith@freemail.example
auth on
user joe.smith
password secret
# A second mail address at the same freemail service
account freemail2 : freemail
from joey@freemail.example
# The SMTP server of the provider.
account provider
host mail.provider.example
from smithjoe@provider.example
auth on
user 123
password pwd
# Set a default account
account default : provider
Create a configuration file for msmtp and add the following lines to your Mutt configuration file:
set sendmail="/path/to/msmtp"
set use_from=yes
set realname="Your Name"
set from=you@example.com
set envelope_from=yes
The `envelope_from=yes' option lets Mutt use the -f option of msmtp. Therefore msmtp chooses the first account that matches the from address you@example.com. Alternatively, you can use the -a option:
set sendmail="/path/to/msmtp -a my_account"
Or set everything from the command line:
set sendmail="/path/to/msmtp --host=mailhub -f me@example.com --tls"
See Choosing an account.
If you have multiple mail accounts in your msmtp configuration file and let Mutt use the -f option to choose one, you can easily switch accounts in Mutt with the following Mutt configuration lines:
macro generic "<esc>1" ":set from=you@example.com"
macro generic "<esc>2" ":set from=you@your-employer.example"
macro generic "<esc>3" ":set from=you@some-other-provider.example"
Now you can use <esc>1, <esc>2, and <esc>3 to switch accounts.
The following example uses a different approach: it maps the single key
<tab> in Compose context for switching between the various account in a
handy visual way. In the same Compose context, = is mapped in order to
show the current msmtp account. This example was contributed by Thomas Baruchel.
# Define <tab> and = in order to switch or see the current msmtp account
# Don't forget to put the right path for msmtp binary
macro compose \Cx_ ":set sendmail"
macro compose \Cx| "\Cx_ = \"/usr/local/bin/msmtp"
macro compose \Cx& ":macro compose \\t \\Cx"
macro compose <tab> "\Cx0"
macro compose = "\Cx_\n"
# Put the account in the following lines (here three accounts)
# Don't forget to put the number of the account at the beginning
# of the line, and the number of the next account after the '&'
macro compose \Cx0 "\Cx|\"\n\Cx&1\n\Cx_\n" # default and switch to 1
macro compose \Cx1 "\Cx| -a example_account\"\n\Cx&2\n\Cx_\n" # switch to 2
macro compose \Cx2 "\Cx| -a gmail\"\n\Cx&0\n\Cx_\n" # switch to 0
# End of the accounts
Define a default account, and put the following into ~/.mailrc:
set sendmail="/path/to/msmtp"
You need to define a default account, because mail does not allow extra options to the msmtp command line.
The homepage of msmtp is http://msmtp.sourceforge.net/; the SourceForge project page is http://sourceforge.net/projects/msmtp/.
The mailing list msmtp-users can be accessed from the project page.
Please send any questions, suggestions, and bug reports either to the mailing
list or to Martin Lambers (marlam@marlam.de, OpenPGP key:
http://www.marlam.de/key.txt).
If you send a bug report, please include the output of msmtp --version.